[es6] parse arrow ConciseBody with accept_IN flag

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index d890ae5c216d7b497d0f3801288bd2fe7c4123fb..fc6294de833c7e06a978c98be281572c39b20f8f 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -714,9 +714,10 @@ class ParserBase : public Traits {
   ExpressionT ParseMemberExpression(ExpressionClassifier* classifier, bool* ok);
   ExpressionT ParseMemberExpressionContinuation(
       ExpressionT expression, ExpressionClassifier* classifier, bool* ok);
-  ExpressionT ParseArrowFunctionLiteral(
-      const FormalParametersT& parameters,
-      const ExpressionClassifier& classifier, bool* ok);
+  ExpressionT ParseArrowFunctionLiteral(bool accept_IN,
+                                        const FormalParametersT& parameters,
+                                        const ExpressionClassifier& classifier,
+                                        bool* ok);
   ExpressionT ParseTemplateLiteral(ExpressionT tag, int start,
                                    ExpressionClassifier* classifier, bool* ok);
   void AddTemplateExpression(ExpressionT);
@@ -1074,6 +1075,9 @@ class PreParserExpression {
 
   PreParserExpression AsFunctionLiteral() { return *this; }
 
+  // Only used by arrow functions with concise bodies, only for lazy parsing.
+  void set_accept_IN(bool value) {}
+
   bool IsBinaryOperation() const {
     return TypeField::decode(code_) == kBinaryOperationExpression;
   }
@@ -2946,7 +2950,7 @@ ParserBase<Traits>::ParseAssignmentExpression(bool accept_IN,
           duplicate_loc);
     }
     expression = this->ParseArrowFunctionLiteral(
-        parameters, arrow_formals_classifier, CHECK_OK);
+        accept_IN, parameters, arrow_formals_classifier, CHECK_OK);
     return expression;
   }
 
@@ -3882,7 +3886,7 @@ bool ParserBase<Traits>::IsNextLetKeyword() {
 template <class Traits>
 typename ParserBase<Traits>::ExpressionT
 ParserBase<Traits>::ParseArrowFunctionLiteral(
-    const FormalParametersT& formal_parameters,
+    bool accept_IN, const FormalParametersT& formal_parameters,
     const ExpressionClassifier& formals_classifier, bool* ok) {
   if (peek() == Token::ARROW && scanner_->HasAnyLineTerminatorBeforeNext()) {
     // ASI inserts `;` after arrow parameters if a line terminator is found.
@@ -3898,6 +3902,7 @@ ParserBase<Traits>::ParseArrowFunctionLiteral(
   int materialized_literal_count = -1;
   int expected_property_count = -1;
   Scanner::Location super_loc;
+  bool concise = false;

[adamk, 2015/10/14 12:46:44]

I don't see this used anywhere (other than it being set to 'true' below), can it
be removed?

[caitp (gmail), 2015/10/14 13:20:18]

probably left over from an older version of the patch, it can go

 
   {
     typename Traits::Type::Factory function_factory(ast_value_factory());
@@ -3936,11 +3941,12 @@ ParserBase<Traits>::ParseArrowFunctionLiteral(
       }
     } else {
       // Single-expression body
+      concise = true;
       int pos = position();
       parenthesized_function_ = false;
       ExpressionClassifier classifier;
       ExpressionT expression =
-          ParseAssignmentExpression(true, &classifier, CHECK_OK);
+          ParseAssignmentExpression(accept_IN, &classifier, CHECK_OK);
       ValidateExpression(&classifier, CHECK_OK);
       body = this->NewStatementList(1, zone());
       this->AddParameterInitializationBlock(formal_parameters, body, CHECK_OK);
@@ -3983,6 +3989,8 @@ ParserBase<Traits>::ParseArrowFunctionLiteral(
       formal_parameters.scope->start_position());
   if (super_loc.IsValid()) function_state_->set_super_location(super_loc);
 
+  function_literal->set_accept_IN(accept_IN);
+
   if (fni_ != NULL) this->InferFunctionName(fni_, function_literal);
 
   return function_literal;